//[]原子表 ()原子组
//[]原子表里有选择符，或者意思
let reg = /[123456]/;
let hd = "121212";
console.log(hd.match(reg));

let regs = /(12|34)/;
let xj = "121212";
console.log(xj.match(regs));
let cm = "2332232222";
console.log(cm.match(regs));
